WO2009033207A1

WO2009033207A1 - Equipment for, and a method of, removing tissue from a site in a patient's body

Info

Publication number: WO2009033207A1
Application number: PCT/AU2008/001271
Authority: WO
Inventors: Ashish Diwan; Zoran Milijasevic; Johnathon Choi
Original assignee: Columna Pty Ltd
Priority date: 2007-09-12
Filing date: 2008-08-28
Publication date: 2009-03-19

Abstract

Equipment (10) for removing tissue from a site in a patient's body includes an elongate, tubular carrier (12) defining a passage. A tissue removal mechanism (22) is arranged at a distal end of the carrier (12). A steering mechanism (18, 20) is associated with the tissue removal mechanism (22) for effecting steering of the tissue removal mechanism (22) about the site. A feed conduit (42) extends through the passage (32) of the carrier (12), the feed conduit (42) being associated with the tissue removal mechanism (22) for feeding fluid into the site to create a pressure differential at the site and to entrain tissue fragments arising from operation of the tissue removal mechanism (22) in the fluid. A removal conduit (44) is in communication with the site, in use, for removing the fluid containing the entrained tissue fragments from the site.

Description

"Equipment for, and a method of, removing tissue from a site in a patient's body"

Cross-Reference to Related Applications

The present application claims priority from United States of America Provisional Patent Application No 60/971,633 filed on September 12, 2007, the contents of which are incorporated herein by reference in their entirety.

Field

This disclosure relates, generally, to the removal of tissue from a site in a patient's body and, more particularly, to equipment for, and a method of, removing tissue from a site in a patient's body. This disclosure relates particularly, but not necessarily exclusively, to the removal of nuclear material from a spinal disc of a patient.

Background

In a number of surgical procedures, tissue removal is required as a preparatory step to inserting a tissue prosthesis at a site in a patient's body. In a number of other surgical procedures, for example, to alleviate pain, it may also be necessary to remove tissue from a site. Increasingly, such surgical procedures are being conducted in a minimally invasive manner as this minimises trauma to surrounding tissue and greatly reduces recovery time. Generally, in surgical procedures conducted in a minimally invasive manner, use is made of a working cannula which is inserted through an incision in a patient's skin to the site to facilitate percutaneous access to the site. Equipment to effect working of tissue at the site, including tissue removal, is inserted through the cannula. It will be appreciated that the diameter of the cannula is reasonably small. Thus, a clinician is constrained in the size of the equipment that can be used at the site. The clinician therefore desires as versatile a piece of equipment as possible in order to effect the most efficient removal of tissue at the site. The applicant is aware of systems for the removal of nuclear tissue from a spinal disc in order to alleviate symptoms arising from herniation of the disc. In such circumstances it is not necessary to remove a significant amount of nuclear material, only enough to relieve the herniation. However, where, for example, the major part of the nucleus is to be removed to enable a nucleus prosthesis to be inserted into the disc, such systems do not provide the necessary degree of efficiency or are not able to remove the majority of the disc nucleus. Summary

According to a first aspect, there is provided equipment for removing tissue from a site in a patient's body, the equipment including an elongate, tubular carrier defining a passage; a tissue removal mechanism arranged at a distal end of the carrier; a steering mechanism associated with the tissue removal mechanism for effecting steering of the tissue removal mechanism about the site; a feed conduit extending through the passage of the carrier, the feed conduit being associated with the tissue removal mechanism for feeding fluid into the site to create a pressure differential at the site and to entrain tissue fragments arising from operation of the tissue removal mechanism in the fluid; and a removal conduit in communication with the site, in use, for removing the fluid containing the entrained tissue fragments from the site. The equipment may include a control arrangement for controlling flow of fluid in at least one of the feed conduit and the removal conduit. The control arrangement may include a pressure monitoring transducer arranged at the distal end of the carrier for detecting the pressure at the site. In addition, or instead, the control arrangement may include a flow rate monitoring unit in at least one of the feed conduit and the removal conduit for monitoring flow rate of the fluid.

A distal region of the carrier may contain a flexible element for permitting bending about the flexible element to effect steering of the distal region of the carrier.

The tissue removal mechanism may be mounted on a drive shaft received in the passage of the carrier, the drive shaft being flexible at least in the region of the flexible element of the carrier to permit bending of the drive shaft.

The tissue removal mechanism may be contained in a housing. The housing may be attached to the distal end of the carrier by the flexible element, the housing defining an opening into which tissue to be removed is drawn by generating a low pressure in the housing via the removal conduit. The equipment may include a handle from which the carrier extends, the handle carrying a steering control assembly for effecting bending of the carrier in the region of the flexible element. The steering control assembly may comprise an axially displaceable element connected to the flexible element and a control member carried by the handle for effecting axial displacement of the axially displaceable element. The tissue removal mechanism may be at least one of a mechanical unit, an ablation unit, an ultrasonic unit and a cryogenics unit. The fluid may include a contrast media to view fluid flow of the fluid in the site, in use, to ensure that it is not being fed to undesirable regions of the site.

According to a second aspect, there is provided a method of removing tissue from a site in a patient's body, the method including accessing the site; inserting a tissue removal mechanism into a desired position at the site and operating the tissue removal mechanism to remove tissue at the site; injecting a fluid into the site while the tissue removal mechanism is operating to create a pressure differential at the site and to entrain tissue fragments in the fluid; and extracting the fluid with the tissue fragments entrained therein from the site.

The method may include accessing the site percutaneously in a minimally invasive manner.

Further, the method may include removing tissue by using at least one of a mechanical unit, an ablation unit, an ultrasonic unit and a cryogenics unit. In an embodiment, the method may include removing the tissue using a mechanical unit that effects at least one of cutting, grinding and breaking off of tissue pieces.

The method may include controlling the flow of fluid to the site. Thus, the method may include controlling the flow of fluid by monitoring pressure of fluid in the site. In addition, or instead, the method may include monitoring flow rate of the fluid during at least one of injecting the fluid into the site and removing the fluid from the site.

The method may include steering the tissue removal mechanism to access as large a part of the site as possible.

The method may include enhancing contact between the tissue removal mechanism and the tissue by maintaining a pressure differential across the tissue removal mechanism. Thus, the method may include maintaining the pressure differential by the use of the fluid.

The method may include adding a contrast media to the fluid to view fluid flow in the site to ensure that it is not being fed to undesirable regions of the site. According to a third aspect, there is provided equipment for removing tissue from a site in a patient's body, the equipment including a handle; a carrier extending from the handle, the carrier defining a passage through it; a housing arranged at a distal end of the carrier, the housing defining a window; a flexible element connecting the housing to the distal end of the carrier to enable the housing to be steered; a rotatable tissue removal mechanism mounted in the housing, the tissue removal mechanism being mounted on the distal end of a drive shaft which extends from the handle through the passage of the carrier, the drive shaft being flexible at least in the region of the flexible element to permit bending of the drive shaft; a feed conduit in communication with the window of the housing for feeding fluid into the site to create a pressure differential at the site and to entrain tissue fragments in the fluid; and a removal conduit in communication with the window of the housing for removing the fluid with the tissue fragments from the site and the housing. According to a fourth aspect, there is provided equipment for removing tissue from a site in a patient's body, the equipment including an elongate, tubular carrier defining a passage; a tissue removal mechanism arranged at a distal end of the carrier; a feed conduit extending through the passage of the carrier, the feed conduit being associated with the tissue removal mechanism for feeding fluid to a zone which enhances contact between the tissue and the tissue removal mechanism; and a removal conduit in communication with the distal end of the carrier for removing the fluid containing entrained tissue fragments from the site.

The zone may be the site itself to encourage displacement of the tissue into contact with the tissue removal mechanism. Instead, or in addition, in the case of an inflatable tissue removal mechanism, the zone may be the interior of the tissue removal mechanism, the fluid being used to inflate the tissue removal mechanism. In this latter case, the fluid may, in some embodiments, be a conductive fluid for energising electrodes carried on a surface of the tissue removal mechanism. According to a fifth aspect, there is provided a method of removing tissue from a site in a patient's body, the method including accessing the site; inserting a tissue removal mechanism into a desired position at the site and operating the tissue removal mechanism to remove tissue at the site; injecting a fluid into one of the tissue removal mechanism and the site while the tissue removal mechanism is operating to encourage contact between the tissue and the tissue removal mechanism; and extracting the fluid with tissue fragments entrained therein from the site.

According to a sixth aspect, there is provided equipment for removing tissue from a site in a patient's body, the equipment including an elongate tubular carrier defining a passage; a feed conduit for feeding a cooling fluid to the site in the patient's body for effecting rapid cooling of at least a part of tissue at the site; and a comminuting means for comminuting the cooled part of the tissue to cause the cooled part of the tissue to be broken up into particles. The comminuting means may be any unit which imparts energy to the cooled part of the tissue. The energy may be heat energy, mechanical energy, acoustic energy (such as vibrational energy), light energy (such as infrared or ultraviolet light), or a combination of the foregoing. In the case of heat energy, the equipment may include a second feed conduit for feeding heated fluid to the cooled part of the tissue. Cooled and heated fluid could be applied to the part of the tissue cyclically in rapid succession to effect fracturing of the part of the tissue.

According to a seventh aspect, there is provided equipment for removing material from a site in a patient's body, the equipment including an elongate carrier defining an entering means at its distal end for enabling the carrier to enter the site; and a material manipulating means carried by the carrier, the material manipulating means for working the material to facilitate removal of the material from the site in the patient's body.

The material to be removed may be tissue at the site or it may be a prosthetic implant which has previously been implanted.

The working of the material may include engaging the material such as ensnaring it, removing the material, or the like.

Brief Description of Drawings Fig. 1 shows a schematic, side view of a first embodiment of equipment for removing tissue from a site in a patient's body;

Fig. 2 shows a side view of a tissue removal mechanism of the equipment of Fig. 1 ;

Fig. 3 shows a three dimensional view of a part of the tissue removal mechanism of the equipment of Fig. 1;

Fig. 4 shows a schematic, side view of the equipment of Fig. 1, in use, with the tissue removal mechanism of the equipment in an initial operative orientation;

Fig. 5 shows a schematic, side view of the equipment of Fig. 1 , in use, with the tissue removal mechanism of the equipment in a further operative orientation; Fig. 6 shows a schematic, side view of a second embodiment of equipment for removing tissue from a site in a patient's body with a tissue removal mechanism of the equipment in a first orientation;

Fig. 7 shows a schematic, side view of the equipment of Fig. 6 with the tissue removal mechanism in a second orientation;

Fig. 8 shows a schematic, side view of a third embodiment of equipment for removing tissue from a site in a patient's body with a tissue removal mechanism of the equipment in a first orientation;

Fig. 9 shows a schematic, side view of the equipment of Fig. 8 with the tissue removal mechanism in a second orientation;

Fig. 10 shows a schematic, side view of a fourth embodiment of equipment for removing tissue from a site in a patient's body with a tissue removal mechanism of the equipment in a first orientation;

Fig. 1 1 shows a schematic, side view of the equipment of Fig. 10 with the tissue removal mechanism in a second orientation;

Fig. 12 shows a schematic, side view of a fifth embodiment of equipment for removing tissue from a site in a patient's body with a tissue removal mechanism of the equipment in a delivery orientation;

Fig. 13 shows a schematic, side view of the equipment of Fig. 12 with the tissue removal mechanism in an initial operative orientation;

Fig. 14 shows a schematic, side view of the equipment of Figs. 12 and 13 with the tissue removal mechanism in a further operative orientation;

Fig. 15 shows a schematic, side view of a sixth embodiment of equipment for removing tissue from a site in a patient's body with a tissue removal mechanism of the equipment in a first orientation;

Fig. 16 shows a schematic, side view of the equipment of Fig. 15 with the tissue removal mechanism in a second orientation;

Fig. 17 shows a schematic, side view of a seventh embodiment of equipment for removing tissue from a site in a patient's body with a tissue removal mechanism of the equipment in a first orientation;

Fig. 18 shows a schematic, side view of the equipment of Fig. 17 with the tissue removal mechanism in a second orientation;

Fig. 19 shows a schematic, side view of an eighth embodiment of equipment for removing tissue from a site in a patient's body; Fig. 20 shows a schematic, side view of a ninth embodiment of equipment for removing tissue from a site in a patient's body; Fig. 21 shows a schematic, side view of a distal part of a tenth embodiment of equipment for removing tissue from a site in a patient's body;

Fig. 22 shows a schematic, side view of a distal part of an eleventh embodiment of equipment for removing tissue from a site in a patient's body; Fig. 23 shows a schematic, side view of a distal part of a twelfth embodiment of equipment for removing tissue from a site in a patient's body;

Fig. 24 shows a schematic, side view of a distal part of a thirteenth embodiment of equipment for removing tissue from a site in a patient's body;

Fig. 25 shows a schematic, side view of a distal part of a first embodiment of equipment for removing material from a site in a patient's body;

Fig. 26 shows a schematic, side view of a distal part of a second embodiment of equipment for removing material from a site in a patient's body; and

Fig. 27 shows a side view of a cutting tool forming a part of the equipment of Fig. 26.

Detailed Description of Exemplary Embodiments

Referring initially to Figs. 1-5 of the drawings, reference numeral 10 generally designates an embodiment of equipment for removing tissue from a site in a patient's body. While the equipment 10 has specific application in the removal of nuclear material from an intervertebral disc, it will be appreciated that the equipment 10 has broader application and can be used where tissue requires removal, for example, in knee surgery, other joint surgery, or the like. For ease of explanation, the equipment 10 will be described with reference to its application in the removal of nuclear material from an intervertebral disc. An intervertebral disc comprises a fibrous annulus known as the annulus fibrosis surrounding a gelatinous nucleus known as the nucleus pulposus. In degenerative disc disease, the nucleus fails and, in conjunction with fissures developing in the annulus fibrosis, may result in herniation of nuclear material which can lead to significant pain if the herniated nuclear material impinges on nerve roots. The equipment 10 comprises a carrier in the form of a tubular probe 12 extending from a handle 14. A housing 16 is arranged at a distal end of the probe 12. The housing 16 includes a flexible element 18 which mounts the housing 16 to the distal end of the carrier 12. The flexible element 18 allows steering or displacement of the housing 16 off the longitudinal axis of the probe by means of a steering control assembly 20 of the handle 14, as will be described in greater detail below. The housing 16 houses a tissue removal mechanism 22 (Fig. 3). In this embodiment, the tissue removal mechanism 22 is a barrel cutter 24 having a plurality of circumferentially spaced, longitudinally extending cutting blades 28. The barrel cutter 24 is mounted on a drive shaft 30. The drive shaft 30 is rotatably mounted in a passage 32 of the probe 12. The drive shaft 30 is sufficiently flexible at least in the region of the flexible element 18 to be able to bend while still transmitting drive to the tissue removal mechanism 22.

A longitudinally extending groove 34 is defined in an outer surface of the probe 12. The groove 34 houses a conductor 36 (Fig. 1) which feeds back pressure information from a pressure monitor 38 (Fig. 2) arranged proximally of the housing 16. The handle includes a display 39 for displaying the pressure detected by the pressure monitor 38. Other monitors could be used in addition to, or instead of, the pressure monitor 38. Thus, a monitor for monitoring the degree of bend of the flexible element 18, such as s train gauge, could be employed as well as other feedback devices. As shown in Fig. 2 of the drawings, the housing defines a window 40 into which tissue to be removed is drawn for cutting by the cutting blades 28 of the tissue removal mechanism 22.

A feed conduit 42 (Fig. 3) is arranged within the passage 32 of the probe 12. The feed conduit 42 opens out into a port (not shown) in the housing 16, the port being diametrically opposed to the window 40 and proximally of the tissue removal mechanism 22, and serves to charge fluid, such as a saline solution, into the site from which tissue is to be removed, as will be described in greater detail below. If desired, the fluid can include a contrast media being a radio opaque contrast media, for example, diatrizoate, to ensure that the fluid which pressurizes the site is not pumped or fed into undesirable areas of the site.

Additionally, a suction or removal conduit 44 is also arranged in the passage 32 of the probe 12 and removes fluid, with tissue fragments entrained therein, from the site for disposal outside the patient's body.

The steering control assembly 20 comprises a threaded element 46 (Fig. 4) axially displaceably arranged in the direction of arrows 48 in the handle 14. A control member in the form of a knurled wheel 50 is rotatably arranged in the handle 14 and is accessible externally of the handle 14. By an operator rotating the knurled wheel 50 the element 46 is displaced axially in the direction of the arrows 48. More particularly, when the wheel 50 is rotated in a first direction, the threaded element 46 is displaced from the position shown in Fig. 4 of the drawings to the position shown in Fig. 5 of the drawings. A cable 52 connects the proximal end of the housing 16 to the element 46. When the element 46 is moved to the position shown in Fig. 5 of the drawings, the cable 52 causes flexure of the flexible element 18 to move the housing 16 off the longitudinal axis of the probe 12. In so doing, the housing 16 can be steered within the site from which the tissue, in the form of nuclear material, is to be removed. The handle 14 further houses a drive motor 54 for rotatably driving the drive shaft 30 and, accordingly, the barrel cutter 24 of the tissue removal mechanism 22.

A longitudinally extending slot 56 is defined in the housing 14 in which a guide pin 58 of the axially displaceable element 46 is received for axially guiding the element 46 relative to the handle 14. In use, the probe 12 is inserted into the nucleus 60 of an intervertebral disc 62 via an opening 64 formed in the annulus or annulus fibrous 66 of the disc 62. It will be appreciated that the opening 64 is formed in the annulus 66 in a minimally invasive manner Likewise, the probe 12 is inserted into the nucleus 60 in a similar minimally invasive manner, for example, through a working cannula (not shown) inserted percutaneously.

The drive motor 54 of the equipment 10 is operated to rotate the barrel cutter 24 of the tissue removal mechanism 22. Simultaneously, fluid is injected into the nucleus 60 from the port via the feed conduit 42 and pressurizes the nuclear tissue 60. This encourages tissue to be urged towards the window 40 of the housing 16 where it is comminuted by the cutting blades 28. A suction is then drawn through the removal conduit 44 so that tissue cut by the blades 28 is entrained in fluid drawn through the removal conduit 44. In addition, the fluid, being in the nucleus 60, entrains pieces of tissue which may have broken off but not have been drawn into the housing 16. This entrained tissue is also drawn up through the removal conduit 44 for disposal outside the patient's body.

To monitor the flow rate of fluid, both in the feed conduit 42 and in the removal conduit 44, flow meters 68 and 70 are mounted in the conduits 42 and 44, respectively. These flow meters 68, 70 can be used instead of, or in conjunction with, the pressure monitor 38. It will be appreciated that the pressure monitor 38 is a pressure transducer which monitors the pressure in the nucleus 60 to ensure that the nucleus is not over pressurized and that fluid is not urged into the annulus 66 of the disc 62.

It will also be appreciated that flow of fluid through the feed conduit 42 does not occur simultaneously with drawing of fluid through the removal conduit 44 but, rather, the passage of fluid through the conduits 42 and 44 occurs sequentially under the action of a controller 71. Thus, when fluid is being withdrawn through the removal conduit 44 flow of fluid through the feed conduit 42 is suspended and, conversely, when fluid is being discharged through the feed conduit 42, drawing of a suction in the removal conduit 44 is suspended. Instead of sequential operation, the controller 71 could operate to maintain a greater flow rate in the feed conduit 42 than the removal conduit 44. Once the tissue has been removed from around the opening 64 of the annulus 66 of the disc 62, the steering control assembly 20 is operated to cause the housing 16 to be steered to the position, for example, shown in Fig. 5 of the drawings to bring the housing 16 into contact with a further quantity of tissue of remaining tissue in the nucleus 60 and the tissue removal procedure is repeated. The tissue removal thus occurs step-wise through the nucleus 60 by steering the housing 16 to the desired position within the nucleus 60 to effect tissue removal. Due to the steerability of the housing 16, a sufficient quantity of tissue of the nucleus 60 can be removed from the disc 62 to enable an artificial prosthetic nucleus to be inserted and implanted via the opening 64 in the annulus 66. It is also beneficial that loose fragments of tissue are entrained in the fluid and are withdrawn through the removal conduit 44 leaving a clear, flushed nuclear cavity in the disc 62 into which the artificial prosthesis can be inserted.

Referring now to Figs. 6 and 7 of the drawings, a second embodiment of equipment 10 for removing tissue is illustrated. With reference to the previous drawings, like reference numerals refer to like parts, unless otherwise specified. In this embodiment, the tissue removal mechanism 22 comprises a blade cutter where blades 72 of a cutter 74 are helically wound about a support member 76.

Further, the steering control assembly 20 comprises an axially displaceable knob 78 which is displaceable in the direction of arrows 80 for effecting bending of the flexible element 18 relative to the probe 12 and, hence, steering of the housing 16.

In Figs. 8 and 9 of the drawings, a third embodiment of equipment for removing tissue from a site in a patient's body is shown. Once again, with reference to the previous drawings, like reference numerals refer to like parts, unless otherwise specified. In this embodiment, the tissue removal mechanism 22 comprises a coring tube

82. The coring tube 82 is, in effect, an extension of the removal conduit 44 and effects tissue removal by reciprocatory action in the direction of arrows 84.

In Figs. 10 and 11 of the drawings, still a further embodiment of equipment for removing tissue from a site in a patient's body is illustrated. With reference to Figs. 1 to 9 of the drawings, like reference numerals refer to like parts, unless otherwise specified. In this embodiment, the tissue removal mechanism 22 comprises a pair of counter-rotating spring-like elements 86. Each element 86 is mounted on its own drive shaft 88.

The drive shafts 88 are mounted in the removal conduit 44. By counter-rotation of the elements 86, nuclear material is trapped between the elements 86 and is broken off for removal through the removal conduit 44.

In Figs. 12-14 of the drawings, a fifth embodiment of equipment for removing tissue from a site in a patient's body is illustrated. As in the previous embodiments, like reference numerals refer to like parts, unless otherwise specified. In this embodiment, the tissue removal mechanism 22 comprises steerable rongeurs 90. The rongeurs 90 comprise a pair of opposable jaws 92 which are used for breaking off pieces of tissue at the site from which the tissue is to be removed. The jaws 92 are pivotally mounted on a pivot pin 94 mounted on the removal conduit 44 so that material broken off by operating the jaws 92 is fed through the removal conduit 44 out of the equipment 10. The jaws 92 are arranged in a normally open configuration and, when contained within the probe 12, lie substantially axially.

The steering control mechanism comprises a compression spring 96 connected between the removal conduit 44 and the free end of one of the jaws 92 of the rongeurs. When the jaws 92 of the rongeurs 90 are extended beyond the probe 12, the spring 96 is activated to pull the rongeurs 90 to the position shown in Fig. 13 of the drawings. The jaws 92 are operated via a trigger mechanism 98.

The embodiments described above all have a tissue removal mechanism 22 which is mechanically operated. In Figs. 15 and 16 of the drawings, a sixth embodiment of equipment for removing tissue from a site in a patient's body is shown. In this embodiment, the tissue removal mechanism 22 comprises an ablation unit. More particularly, the tissue removal mechanism 22 comprises a balloon 100 on which a plurality of circumferential, axially spaced electrodes 102 are mounted. The balloon 100 is inflated via an inflation port 101. The balloon 100 is contained in a collapsed configuration within the probe 12 to be delivered into position in the nucleus 60 of the disc 62. When the probe 12 is inserted through the opening 64 in the annulus 66 of the disc 62, the balloon 100 is urged out of the distal end of the probe 12 and is expanded to the condition shown in Fig. 16 of the drawings.

The electrodes 102 are connected via conductors, one of which is shown at 104, to an RF generator 106. The generator 106 generates RF energy which is fed via conductors 108 and the conductors 104 to a selected pair or pairs of electrodes 102, the electrodes 102 of each pair being of opposite polarity to effect ablation between them. Thus, the energised pair of electrodes 102 of the balloon 100 cause ablation of the tissue of the nucleus 60 of the disc 62 for subsequent removal of burned or charred nuclear material through the removal conduit (not shown). The passage of the probe 12 could be used as the removal conduit 44. It will be appreciated that, instead of the balloon 100, the tissue removal mechanism could be a loop device which is expanded as it is extended from the distal end of the probe 12, the loop device effecting the ablation. By rotating the loop device a "scoop" of nuclear material can be removed.

In Figs. 17 and 18 of the drawings, yet a further embodiment of equipment for removing tissue from a site in a patient's body is illustrated and, once again, with reference to the previous drawings, like reference numerals refer to like parts, unless otherwise specified.

In this embodiment, the tissue removal mechanism 22 comprises a plurality of preformed wires 1 10. These wires 110 are pre-formed from a shape memory alloy material such as, for example, Nitinol. The wires are preformed to expand radially outwardly when extended from the distal end of the probe 12. Thus, as shown in Fig. 17 of the drawings, the wires 110 are, initially, constrained within the probe 12 for delivery to the site. At the site, the wires 110 are extended from the distal end of the probe 12 and splay outwardly as shown in Fig. 18 of the drawings into their pre-formed orientation. The wires 1 10 are connected via conductors 1 12 to the RF generator 106. The RF generator feeds RF energy via the conductors 1 12 to one or more of the wires 1 10 to effect ablation of the tissue and subsequent removal of charred or burnt tissue via the removal conduit (not shown).

In Fig. 19 of the drawings, yet a further embodiment of equipment for removing tissue from a site in a patient's body is illustrated. As in the previous embodiments, like reference numerals refer to like parts, unless otherwise specified.

In this embodiment, the tissue removal mechanism 22 is an ultrasonic unit and comprises a plurality of nested tubes 114 which are arranged to be displaced axially with respect to each other in the direction of arrows 1 16. The tubes 1 14 are connected via a conductor 1 18 to an ultrasonic console 120.

The tubes 1 14 are excited at an ultrasonic frequency by the ultrasonic console 120 causing the tubes to vibrate reciprocally with respect to one another in the direction of arrows 116. Any nuclear material caught between the tubes 114 is finely ground up and removed via the removal conduit 44. In Fig. 20 of the drawings, still a further embodiment of equipment for removing tissue from a site in a patient's body is illustrated and, with reference to the previous embodiments, like reference numerals refer to like parts, unless otherwise specified.

In this embodiment, the tissue removal mechanism 22 is, once again, an ultrasonic unit and comprises a reciprocatory tube or wire 122 which is arranged to reciprocate relative to the removal conduit 44. The tube or wire 122 is excited at an ultrasonic frequency by the ultrasonic console 120 via the conductor 118. This causes the tube or wire 122 to vibrate reciprocally with respect to the removal conduit 44 to effect destruction of nuclear material to be removed via the removal conduit 44. It is to be noted that, in all the embodiments described above, the nucleus 60 is positively pressurised by fluid discharged from the feed conduit 42. This advantageously assists in urging nuclear material into contact with the relevant tissue removal mechanism 22 and assists in removal of tissue fragments either directly through the removal conduit 44 or by being entrained in fluid drawn through the removal conduit 44 out of the disc 62.

It is therefore a particular advantage of embodiments that equipment 10 is provided which, by relying on a pressure differential across the tissue removal mechanism 22, urges tissue to be removed into contact with the tissue removal mechanism. This results in more efficient tissue removal. In addition, loose fragments of tissue are entrained in fluid to be withdrawn from the site via the removal conduit 44. This flushes the site of loose nuclear material resulting in a far cleaner cavity being formed than would otherwise be the case.

The ability to steer the tissue removal mechanism 22 also aids in more efficient removal of tissue from the site forming a cleaner cavity in which the prosthesis can be inserted. Another advantage of a steerable tissue removal mechanism 22 is that the working cannula by which the site is accessed can be smaller meaning a smaller incision and reduced trauma to surrounding tissue.

In Fig. 21 of the drawings, still another embodiment of equipment for removing tissue from a site in a patient's body is illustrated and, with reference to the previous embodiments, like reference numerals refer to like parts, unless otherwise specified.

In this embodiment, the equipment 10 comprises development of the embodiment illustrated in Figs. 15 and 16 of the drawings. It will be appreciated that, because use is made of an inflatable device such as a balloon 100 as an ablation unit, it is not essential that the balloon be steerable. As the balloon 100 expands, it conforms to the shape of the cavity generated as a result of removal of nuclear tissue from the disc 62. Further, after each ablation step, the balloon 100 is able to be expanded further to conform to the shape of the cavity formed in the disc.

In this embodiment, a plurality of spaced, substantially disc-shaped electrodes 130 are arranged on an outer surface of the balloon 100. It will be appreciated that the electrodes 130 could be of any suitable shape and need not be disc-shaped. For example, the electrodes 130 could be in the form of plates, bands extending about the circumference of the balloon 100, nodules, or the like. Still further, the electrodes 130 could be implemented as conductive parts of the outer surface or a wall of the balloon 100. Instead, the conductive parts of the surface or wall of the balloon 100 could be used as conductors for conveying RF energy to the electrodes 130 arranged on the balloon 100. These conductive parts may be of a silicone, silicone composite or other polymer, polymer-metal or polymer-polymer composite materials. An advantage of using such conductive parts of the balloon 100 itself is that the conductive parts are able to stretch elastically as the balloon 100 is inflated. Each electrode 130 is connected to a source of RF energy (not shown in this embodiment but which is the same as, or similar to, the RF generator 106 of the Figs. 15 and 16 embodiment) via an electrical lead 132. Each lead 132 extends through the feed conduit 42 from the RF generator to exit the feed conduit 42 at a distal region of the feed conduit 42. Each lead 132 is an extensible lead, for example, configured like a telephone cord between a base and telephone handset, to be able to extend as the balloon 100 expands under the action of a filler fluid. The configuration of each lead 132 also facilitates twisting or bending of the lead 132 as the balloon 100 expands or is manipulated.

The leads 132 may be connected via a universal connector (not shown) to the RF generator. The RF generator has a readout of impedance to show whether the selected electrode/s 130 is/are in contact with the tissue or whether the tissue in contact with the electrode/s 130 has been ablated. It will be appreciated that there will be a change in impedance after ablation of the tissue. Ablation temperatures may be less than about 4O⁰C, between about 40-60⁰C, between about 60-80⁰C, or greater than about 8O⁰C. The leads 132 are, preferably, of low resistance metals such as platinum, gold, silver, or the like or other suitable low resistance composites etc.

Another design of the lead 132 is as a tube arrangement or configuration. A wall of the tube is of a conductive material, a conductor is co-axially arranged in the tube to exit through a distal end of the tube, a conductor is helically wound about or in the tube or in a wall of the tube or a conductive fluid is used to energise the electrode 130. This arrangement facilitates expansion of the balloon 100. The tube delivers a cooling fluid to its associated electrode 130. It will be appreciated that the cooling fluid could be the conductive fluid and/or a radio-opaque fluid.

The balloon 100 surrounds the distal region of the filler conduit 42 and a neck 134 of the balloon seats sealingly about the feed conduit 42. A discharge port 134 is arranged in the distal region of the feed conduit 42 to place the interior of the balloon in communication with the interior of the feed conduit 42. The balloon 100 is expanded under the action of the filler fluid discharged from the feed conduit 42 into the interior of the balloon 100.

A return electrode 138 is arranged on, but is electrically isolated from, a distal end of the feed conduit 42. The return electrode 138 is arranged on the outer surface of the balloon 100 and allows bipolar operation using one or more selected electrodes 130. In this embodiment, the electrodes 130 are individually selectable so that desired regions of the tissue can be ablated. It will be appreciated that, for monopolar operation, an indifferent electrode (not shown) is arranged externally of the patient. A selective or targeted ablation can be achieved by inflating the balloon 100 in the cavity and selectively energizing the desired electrode/s 130. The position of the electrodes 130 can be visualized through x-ray imaging (in real time if required) and the specific electrodes can be energized to effect the tissue ablation.

The fluid can be any suitable filler fluid such as air, water, saline, radio-opaque dye, a biomaterial, combinations of the foregoing, or the like.

The balloon 100 is either of an elastic material or of an inelastic material. An example of an elastic material includes silicone. An example of an inelastic material includes PET. The stiffness and/or wall thickness of the balloon 100 can be preset in order to control the expansion of the balloon 100 and, hence, to control the size and/or shape of the cavity. For example, if a central, circumferential band of the balloon 100 is portions of opposed sides of the band are made to be elastic, soft, and/or thin walled, then the expansion of the balloon 100 may be directed parallel to a longitudinal axis of the probe 12. Similarly, radial expansion is restricted.

The direction of expansion is only limited by the constraints of the balloon 100. If a known, certain size of cavity were to be achieved, a significantly inelastic material can be used for the balloon 100. If the balloon 100 were a fixed size and or shape, then it will only be able to inflate to its preformed size (beyond which it cannot expand or stretch much further); hence the shape and size of the cavity being created can be predetermined. This embodiment includes an optional secondary feed conduit 140 which pressurizes the site with fluid and encourages contact between the tissue and the electrodes 130. The conduit 140 could be omitted and the same effect achieved by expansion of the balloon 100. However, the provision of the conduit 140 assists with irrigation of the site and entraining of ablated tissue fragments for extraction by the removal conduit 44. In this embodiment, the removal conduit 44 is implemented as at least a part of the passage of the probe 12. The irrigation fluid may assist with conductivity between the tissue being ablated and the electrodes 130.

Referring now to Fig. 22 of the drawings, a variation of the Fig. 21 embodiment is illustrated, with, once again, like reference numerals referring to like parts unless otherwise specified. In this embodiment, the leads 132 are omitted. Instead, each electrode 130 has a conductive mounting portion 142 arranged on an inner surface of the balloon 100. The filler fluid used is an ionic conductive fluid for causing conduction of RF energy by all of the electrodes 130 when energy is applied to the fluid by the RF generator (not shown in this embodiment but, once again, the same as, or similar to, the RF generator of the Figs. 15 and 16 embodiment). Thus, ablation is effected by all the electrodes 130 simultaneously using the return electrode 138 as a return path.

Preferably, the conductive fluid is also radio-opaque so that the size of the cavity being formed can be monitored.

It will be appreciated that, in this embodiment, the absence of the leads 132, minimizes the likelihood of incorrect operation or failure to operate arising from short- circuiting leads, breaking of leads, or the like.

Ablating tissue by means of radiofrequency electrode/s is advantageous in that it results in fast patient recovery making hospital stays shorter, significantly lower operating cost, and lessens the risk of post- surgery side-effects, as compared with other surgical operation methods.

The above embodiments have several functions. They have the ability to ablate tissue, size the cavity and treat pain at the same time. If required, the pressure of inflating the balloon 100 may also distract and or mobilize a collapsed disc. The electrical current which passes between the electrodes 130 will ablate the tissue and can also perform the function of an intradiscal electrothermal anuloplasty (IDETA) which ablates the pain sensing nerve endings around the disc. As the balloon 100 is being inflated with a radio-opaque dye, the size of the cavity can be monitored on x-ray, fluoroscope, CT, or the like.

Further, as an ongoing treatment method, a percutaneous lead may be provided (or conduction may be through an inductive coil) which is connectable to an RF console, allowing for further IDETA (or similar) treatment with the electrical current (for pain) at a later stage.

In Figs. 23 and 24, two embodiments of equipment for removing tissue from a site in a patient's body using a cryogenic unit is illustrated. Once again, with reference to the previous embodiments, like reference numerals refer to like parts unless otherwise specified.

The equipment 10 includes the feed conduit 42 which has a distal discharge opening 150 through which a cooling fluid is discharged into the disc. By "cooling" is typically meant that the fluid freezes the tissue of the nucleus 62 of the disc 60 but this embodiment is not limited to cryogenic fluids and includes within its scope any fluid which effects rapid cooling of the tissue. For ease of explanation, the embodiment will be described with reference to the use of cryogenic fluids such as liquid nitrogen or liquid ethane.

In use, the cryogenic fluid is concentrated in a small area to localize the effect of the cryogenic fluid and to minimize damage to surrounding areas. Once the part of the tissue has been frozen or cooled, energy is applied to that part of the tissue to cause fracture and comminuting of the part of the tissue. The energy may be heat energy, mechanical energy, acoustic energy (such as vibrational energy), light energy (such as infrared or ultraviolet light), or a combination of the foregoing. The comminuted tissue particles are entrained in fluid and are withdrawn through the removal conduit 44 which, in these embodiments, is implemented as at least a part of the passage of the probe 12. The tissue particles may be less than about 1 micron, between about 1-10 microns, between about 10-100 microns, between about 100-1000 microns or greater than about 1000 microns. In the embodiment shown in Fig. 23, once the part of the tissue has been frozen or otherwise cooled, the part of the tissue is subjected to mechanical energy by the distal tip of the feed conduit 42 reciprocating in the direction of arrows 152. In addition, or instead, the frozen/cooled part of the tissue is subjected to ultrasonic energy from an ultrasonic transducer 154 contained in the distal tip of the feed conduit 42. The ultrasonic transducer 154 is connected to a source of ultrasonic energy (not shown in this embodiment but being the same as, or is similar to, the ultrasonic console 120 of the embodiments shown in Figs. 19 and 20).

In the embodiment shown in Fig. 24, once the part of the tissue has been frozen or otherwise cooled, the part of the tissue is subjected to mechanical energy via a burr like structure 156 carried at the distal end of the feed conduit 42. Still further, fragmentation or fracturing of the part of the tissue can occur through rapid freezing and heating which can result in the part of the tissue fracturing. If necessary, the rapid freezing and/or heating can occur cyclically to stress the specimen repeatedly and cause a stress fracture to occur. This may be effected by using the removal conduit 44 for the delivery of heated fluid after the cooling fluid has been delivered by the feed conduit 42.

In a related aspect, those skilled in the art will appreciate that an implant has a finite lifespan which, generally, is about ten years or so. After that time it will be necessary to remove the implant and replace it with a new implant. It is desirable to achieve this in a minimally invasive manner to reduce patient trauma and recovery time.

Therefore, referring to Figs. 25-27, embodiments of equipment for removing an implant are illustrated. While the term "explant" relates generally to living tissue, it will be used to refer to removal of the prosthetic intervertebral disc nucleus. Also, while these embodiments are described with reference to their application in the explanting of a prosthetic disc nucleus, it will be appreciated that the equipment could be used in any application where a prosthetic implant is to be explanted.

In Fig. 25, a first embodiment of equipment for explanting an implant is illustrated and is designated generally by the reference numeral 200. The equipment 200 includes trocar 202 defining a passage 204. The trocar 202 has an entering means in the form of a spiked distal tip 206. Laterally opening ports 208 are defined proximally of the tip 206.

An implant manipulating means in the form of an ensnaring mechanism 210 is displaceably received in the passage 204 of the trocar 202. Prior to placement of the tip 206 of the trocar 202 at the desired position relative to an implant 212 to be explanted, a distal part 214 of the ensnaring mechanism 210 is arranged proximally of the ports 208. The distal part 214 of the ensnaring mechanism comprises a plurality of barbs 216. Preferably, there are the same number of barbs 216 as there are ports 208 but it will be appreciated that there could be fewer barbs 216 than there are ports 208. Also, instead of having the distal part 214 of the ensnaring mechanism 210 arranged proximally of the ports 208 prior to use, the barbs 216 could lie in the same plane as the ports 208 but out of alignment or register with the ports 208.

At least the distal part of the 214 of the ensnaring mechanism 210 is of a shape memory alloy which is preformed so that, when the barbs 216 are no longer constrained by the trocar 202, the barbs 216 splay radially outwardly. The shape of the ports 208 assists in guiding the barbs 216 and causing them to splay outwardly. Thus, in use, the trocar 202 is inserted percutaneously through an incision made in the patient's skin via an introducer (not shown). Either an annulotomy is first performed on the annulus of the intervertebral disc or the tip 206 of the trocar 202 can be used to perform the annulotomy. Once access has been gained to the nucleus of the disc, the trocar 202 is driven through the disc. When the trocar 202 is in the desired position, the ensnaring mechanism 210 is displaced either axially or rotationally, as the case may be, to bring the barbs 216 into register with the ports 208. As the barbs 216 come into register with the ports 208, the barbs 216 protrude through the ports 208 and engage the material of the implant 212. Further working of material of the implant, for example, as described with reference to the Figs. 26 and 27 described below, can be effected.

In the embodiment shown in Figs. 26 and 27, the equipment 200 includes the trocar 202 having the spiked tip 206. In this embodiment, the implant manipulating means of the equipment 200 comprises a plurality of cutting tools 220, only one of which is shown. The cutting tools 220 are of different diameters to fit about the outside of the trocar 202. Each cutting tool 220 is mounted on the trocar 202 via a spacer 222. Further, each cutting tool 220 has a serrated distal end 224.

In use, the trocar 202 is inserted percutaneously in a minimally invasive manner using an introducer as described above with reference to the previous embodiment. The tip 206 of the trocar 202 is used to perform an annulotomy on the annulus of the disc or the annulotomy is performed as a preceding step.

Once positioned relative to the implant 212, a first cutting tool 220 of smallest diameter is placed about the trocar 202 and is driven distally through the implant 212 to cut the implant with a coring action. After the first core of implant material has been removed, the trocar 202 with the first cutting tool 220 is removed from the introducer and the cutting tool 220 is replaced with another cutting tool 220 of larger diameter than the preceding cutting tool 220. The trocar 202 is re-inserted via the introducer into the disc and the cutting tool 220 is operated to core out a further part of the implant 21. The procedure is repeated with progressively larger cutting tools 220 until substantially all of the implant 212 has been removed.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the specific embodiments without departing from the broadly described scope. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims

CLAIMS:

1. Equipment for removing tissue from a site in a patient's body, the equipment including an elongate, tubular carrier defining a passage; a tissue removal mechanism arranged at a distal end of the carrier; a steering mechanism associated with the tissue removal mechanism for effecting steering of the tissue removal mechanism about the site; a feed conduit extending through the passage of the carrier, the feed conduit being associated with the tissue removal mechanism for feeding fluid into the site to create a pressure differential at the site and to entrain tissue fragments arising from operation of the tissue removal mechanism in the fluid; and a removal conduit in communication with the site, in use, for removing the fluid containing the entrained tissue fragments from the site.

2. The equipment of claim 1 which includes a control arrangement for controlling flow of fluid in at least one of the feed conduit and the removal conduit.

3. The equipment of claim 2 in which the control arrangement includes a pressure monitoring transducer arranged at the distal end of the carrier for detecting the pressure at the site.

4. The equipment of claim 2 or claim 3 in which the control arrangement includes a flow rate monitoring unit in at least one of the feed conduit and the removal conduit for monitoring flow rate of the fluid.

5. The equipment of any one of the preceding claims in which a distal region of the carrier contains a flexible element for permitting bending about the flexible element to effect steering of the distal region of the carrier.

6. The equipment of claim 5 in which the tissue removal mechanism is mounted on a drive shaft received in the passage of the carrier, the drive shaft being flexible at least in the region of the flexible element of the carrier to permit bending of the drive shaft.

7. The equipment of claim 5 or claim 6 in which the tissue removal mechanism is contained in a housing.

8. The equipment of claim 7 in which the housing is attached to the distal end of the carrier by the flexible element, the housing defining an opening into which tissue to be removed is drawn by generating a low pressure in the housing via the removal conduit.

9. The equipment of any one of claims 5 to 8 which includes a handle from which the carrier extends, the handle carrying a steering control assembly for effecting bending of the carrier in the region of the flexible element.

10. The equipment of claim 9 in which the steering control assembly comprises an axially displaceable element connected to the flexible element and a control member carried by the handle for effecting axial displacement of the axially displaceable element.

1 1. The equipment of any one of the preceding claims in which the tissue removal mechanism is at least one of a mechanical unit, an ablation unit, an ultrasonic unit and a cryogenics unit.

12. The equipment of any one of the preceding claims in which the fluid includes a contrast media to view fluid flow of the fluid in the site, in use, to ensure that it is not being fed to undesirable regions of the site.

13. A method of removing tissue from a site in a patient's body, the method including accessing the site; inserting a tissue removal mechanism into a desired position at the site and operating the tissue removal mechanism to remove tissue at the site; injecting a fluid into the site while the tissue removal mechanism is operating to create a pressure differential at the site and to entrain tissue fragments in the fluid; and extracting the fluid with the tissue fragments entrained therein from the site.

14. The method of claim 13 which includes accessing the site percutaneously in a minimally invasive manner.

15. The method of claim 13 or claim 14 which includes removing tissue by using at least one of a mechanical unit, an ablation unit, an ultrasonic unit and a cryogenics unit.

16. The method of claim 15 which includes removing the tissue using a mechanical unit that effects at least one of cutting, grinding and breaking off of tissue pieces.

17. The method of any one of claims 13 to 16 which includes controlling the flow of fluid to the site.

18. The method of claim 17 which includes controlling the flow of fluid by monitoring pressure of fluid in the site.

19. The method of claim 17 or claim 18 which includes monitoring flow rate of the fluid during at least one of injecting the fluid into the site and removing the fluid from the site.

20. The method of any one of claims 13 to 19 which includes steering the tissue removal mechanism to access as large a part of the site as possible.

21. The method of any one of claims 13 to 20 which includes enhancing contact between the tissue removal mechanism and the tissue by maintaining a pressure differential across the tissue removal mechanism.

22. The method of claim 21 which includes maintaining the pressure differential by the use of the fluid.

23. The method of any one of claims 13 to 22 which includes adding a contrast media to the fluid to view fluid flow in the site to ensure that it is not being fed to undesirable regions of the site.

24. Equipment for removing tissue from a site in a patient's body, the equipment including a handle; a carrier extending from the handle, the carrier defining a passage through it; a housing arranged at a distal end of the carrier, the housing defining a window; a flexible element connecting the housing to the distal end of the carrier to enable the housing to be steered; a rotatable tissue removal mechanism mounted in the housing, the tissue removal mechanism being mounted on the distal end of a drive shaft which extends from the handle through the passage of the carrier, the drive shaft being flexible at least in the region of the flexible element to permit bending of the drive shaft; 5 a feed conduit in communication with the window of the housing for feeding fluid into the site to create a pressure differential at the site and to entrain tissue fragments in the fluid; and a removal conduit in communication with the window of the housing for removing the fluid with the tissue fragments from the site and the housing. 1.0

25. Equipment for removing tissue from a site in a patient's body, the equipment including an elongate, tubular carrier defining a passage; a tissue removal mechanism arranged at a distal end of the carrier;

15 a feed conduit extending through the passage of the carrier, the feed conduit being associated with the tissue removal mechanism for feeding fluid to a zone which enhances contact between the tissue and the tissue removal mechanism; and a removal conduit in communication with the site, in use, for removing the fluid containing entrained tissue fragments from the site. 20

26. A method of removing tissue from a site in a patient's body, the method including accessing the site; inserting a tissue removal mechanism into a desired position at the site and 25 operating the tissue removal mechanism to remove tissue at the site; injecting a fluid into one of the tissue removal mechanism and the site while the tissue removal mechanism is operating to encourage contact between the tissue and the tissue removal mechanism; and extracting the fluid with tissue fragments entrained therein from the site. 30